94 PAIR removal update

[Ppleasants]

Am I missing something here or are people grossly oversimplifying the process of removing the PAIR system? First of all, the nuts on the studs from the manifold were nearly impossible to remove and I managed to bend one of the studs. I managed to gash my thumb down to the bone in the process of removing the giant bundle of metal vacuum lines under the throttle body/intake.. The two bolts holding that in place were not easy to get at. And even after unbolting that mess, I have yet to figure out a way to remove it from between the two intake halves. When I DO manage to get that out, I'm still unsure what to do with the 6 or more vacuum lines that are now left open.

Are people taking the throttle body off (I can but just replaced the gasket when doing the valve cover gasket and would prefer not to replace again)? Are people also removing the EGR system in conjunction with the PAIR system (is that where all those vacuum lines go... I literally can't see where they end up)? Any help would be greatly appreciated.

 

[bigredmachine]

Am I missing something here or are people grossly oversimplifying the process of removing the PAIR system? First of all, the nuts on the studs from the manifold were nearly impossible to remove and I managed to bend one of the studs. I managed to gash my thumb down to the bone in the process of removing the giant bundle of metal vacuum lines under the throttle body/intake.. The two bolts holding that in place were not easy to get at. And even after unbolting that mess, I have yet to figure out a way to remove it from between the two intake halves. When I DO manage to get that out, I'm still unsure what to do with the 6 or more vacuum lines that are now left open.

Are people taking the throttle body off (I can but just replaced the gasket when doing the valve cover gasket and would prefer not to replace again)? Are people also removing the EGR system in conjunction with the PAIR system (is that where all those vacuum lines go... I literally can't see where they end up)? Any help would be greatly appreciated.

to remove the vsv's you will need to remove the upper intake, your not going to be able to sneak them out. the open vacuum lines you can just cap and call a day. if you remove the throttle body you can just reuse the gasket, its a metal gasket and it should be fine.

you don't have to remove the egr at the time of pair removal, I have my egr disabled and still have the pair for now

 

[Ppleasants]

to remove the vsv's you will need to remove the upper intake, your not going to be able to sneak them out. the open vacuum lines you can just cap and call a day. if you remove the throttle body you can just reuse the gasket, its a metal gasket and it should be fine.

you don't have to remove the egr at the time of pair removal, I have my egr disabled and still have the pair for now

I really appreciate the quick response. I managed to get two of the bolts out but I found some photos that seem to show a third? But you’re saying even if I get that off, I’ll have to split the intake?

I guess I’ll pull the throttle body and see what I can get to at that stage and if need be, pull the intake. EGR should still operate fine with no codes though? My whole purpose for removing the PAIR is to relocate O2 sensors to the exhaust manifold to eliminate my CEL code 26.

 

[bigredmachine]

My whole purpose for removing the PAIR is to relocate O2 sensors the the exhaust manifold to eliminate my CEL code 26.

relocating the o2 sensor probably wont fix the 26 code, you should test the o2 sensors to see if their still good and relocate or replace as needed. if you do need o2 sensors go with denso or ngk sensors. relocating isn't a bad idea, just may not fix your issue.

personally I havnt pulled all the vsv's out but any pics that I have seen of others removing htan they have had the intake split to pull it all out

 

[Ppleasants]

relocating the o2 sensor probably wont fix the 26 code, you should test the o2 sensors to see if their still good and relocate or replace as needed. if you do need o2 sensors go with denso or ngk sensors. relocating isn't a bad idea, just may not fix your issue.

personally I havnt pulled all the vsv's out but any pics that I have seen of others removing htan they have had the intake split to pull it all out

I've actually got a new OEM Toyota O2 sensor waiting to go in. One of them has been failing recently and there may be a correlation with wet weather. I figured I would replace and relocate as a preventative measure.

I managed to get the other TWO bolts out (4 in total) holding all the guts between the two intake halves (after pulling the throttle body but NOT the upper intake). I had to mangle the bracket a little bit and unscrew some of the components (I guess VCVs?) from it but I managed to pull everything out bit by bit. Just to clarify, my intent is to keep the EGR system wholly intact... I'm not sure if I've already gone too far to accomplish that or not.

I'll have to go back through and cap all the vacuum lines. There seem to be a lot (7 in total) if anyone can help me to verify these (vacuum systems are not my forte):

- one large barbed fitting on the intake under the flange to the throttle body
- two fittings on one plastic piece threaded into the block just below the intake
- one of the two fittings on one plastic piece threaded into the top of the intake (one will be run to the fuel rail as seen in another post)
- one small fitting on top of TB
- one large fitting on top of TB
- one small fitting on the bottom side of the upper intake, towards the firewall

 

[TerraNerva]

On my '94, I just looped the two vac lines (the ones opposite your #5 and #6) back on themselves to disable, and jumped the temp sensor for OBDI (or resistors for OBDII). From what I read and understood, just disable the vac 'supply' to the system and it will no longer be active, and then fool the temp sensor and you're done. Not sure all that you're doing is necessary if you intend to leave it intact. I could be wrong, maybe someone else will chime in and confirm.

 

[Ppleasants]

On my '94, I just looped the two vac lines (the ones opposite your #5 and #6) back on themselves to disable, and jumped the temp sensor for OBDI (or resistors for OBDII). From what I read and understood, just disable the vac 'supply' to the system and it will no longer be active, and then fool the temp sensor and you're done. Not sure all that you're doing is necessary if you intend to leave it intact. I could be wrong, maybe someone else will chime in and confirm.

Thanks for the info. I realize that I've gone WAY further than I intended. The photos by @ajax1 of the removed fuel pressure, EVAP, PAIR, and EGR VCVs mislead me into thinking this was all part of the PAIR removal.. I should have dived deeper. Ajax, have you had any issues since going this route?

I'm considering putting it all back and just capping the single vacuum line that leads to the PAIR system over by the exhaust. Even if I did decide to disable the EGR, I'd prefer to keep the EVAP and fuel pressure VCVs intact.

By the way, all of this CAN be done with the upper intake intact. I wouldn't recommend it, though, and if I replace I'll probably pull it.

 

[ajax1]

Thanks for the info. I realize that I've gone WAY further than I intended. The photos by @ajax1 of the removed fuel pressure, EVAP, PAIR, and EGR VCVs mislead me into thinking this was all part of the PAIR removal.. I should have dived deeper. Ajax, have you had any issues since going this route?

I'm considering putting it all back and just capping the single vacuum line that leads to the PAIR system over by the exhaust. Even if I did decide to disable the EGR, I'd prefer to keep the EVAP and fuel pressure VCVs intact.

By the way, all of this CAN be done with the upper intake intact. I wouldn't recommend it, though, and if I replace I'll probably pull it.

View attachment 1668760

I have no issues my truck is a 94, only vacuum line is to the fps and there is one other you must keep that goes under the tps from the throttle body that is hidden until you pull the iac, I have no egr no pair. The lines you are pulling some are for the egr as well as the vsv you need for egr, at the point you are out you need to disable the egr also, and your charcoal canister will now vent to atmosphere instead of back into the manifold since that is in the stuff you pulled also

 

[ajax1]

@Ppleasants to do just your pair system, pull the pair pipes and cap the manifolds or put your o2s there or run 95 plus manifolds. Remove the hose from top plug it on the air box. You can get a clip for your throttle cable from 95 plus engine, and you can update to the different style coolant return line eliminating the rubber hose

 

[TerraNerva]

So, I have a related question: I have disabled the EGR as I described above, without removing any additional components leaving it intact. One of the vacuum hose from the charcoal canister is still hooked up to the VSV. Since the EGR is disabled, is there a problem with canister not venting to the atmosphere other than the connected line that does this as a normal function? I don't want to shorten the life of the new canister. It does have the line to tank attached, as well as the one that is open to engine compartment line and the line to the now disabled VSV, so it is hooked up as if the EGR system is functioning. If it is sending fuel vapors to a disabled system, I don't want any potential fire or related issues. Any thoughts? If I understand the EGR system operation, the EGR only operates at higher speeds/RPMs anyway.

 

[ajax1]

Egr burns exhaust gases, charcoal canister burns out the fuel vapor thru the intake

 

[Ppleasants]

So, I have a related question: I have disabled the EGR as I described above, without removing any additional components leaving it intact. One of the vacuum hose from the charcoal canister is still hooked up to the VSV. Since the EGR is disabled, is there a problem with canister not venting to the atmosphere other than the connected line that does this as a normal function? I don't want to shorten the life of the new canister. It does have the line to tank attached, as well as the one that is open to engine compartment line and the line to the now disabled VSV, so it is hooked up as if the EGR system is functioning. If it is sending fuel vapors to a disabled system, I don't want any potential fire or related issues. Any thoughts? If I understand the EGR system operation, the EGR only operates at higher speeds/RPMs anyway.

CORRECTION IN RED:

I did a little investigating with the parts I pulled and here is what I found:

The charcoal canister feeds into that little blue/black valve which is triggered to open by vacuum from the block just below the intake manifold (not the VCV). If there is no vacuum to that valve, it won't open. When there is vacuum and the valve is open, the gases from charcoal canister flow to the larger nipple on the very top of the throttle body. I believe as long as you haven't unplugged or removed the VCV for the evap system under the intake plenum, your valve should still operate as intended and gases should flow directly to the throttle body. The function of the blue/black valve looks to be independent of the VCVs but I could very well be wrong.

Photo is incorrect: that vacuum line goes to the block just below the intake manifold, NOT the VCV. Still no clue on the other small vacuum port

 

[Ppleasants]

@cDan and any others that care to chime in: I'm confused about which gaskets I should use where. The gasket for the PAIR-to-manifold faces are different than those for the O2-to-exhaust faces. Which should I use for the new O2 placement at the exhaust manifold? Which should I use for the OEM block-off plates for the original O2 sensor location?

I ordered the gasket for the PAIR system (17376-66010) as mentioned in this thread but am more inclined to use the gasket intended for the O2 sensor. My one new O2 sensor came with a gasket but I'll be using the other original sensor and will need to replace that gasket. I'm thinking of ordering x3 O2 sensor gaskets to use for the remaining O2 sensors and under the block-off plates. Any insight will be helpful

 

[ajax1]

@Ppleasants what are you trying to do? If your putting o2s in the manifold new o2 come with gaskets, just leave the old o2s in the exhaust as block offs as long as they don't leak, or build some plates for that. You need to remove the full pair system

 

[Ppleasants]

@Ppleasants what are you trying to do? If your putting o2s in the manifold new o2 come with gaskets, just leave the old o2s in the exhaust as block offs as long as they don't leak, or build some plates for that. You need to remove the full pair system

Yeah, I've removed the complete PAIR system and I'm relocating the O2 sensors to the exhaust manifold. I'm only replacing one of the sensors so I only have one new gasket. Both O2 sensors came out no problem and in their place will go block-off plates. Several people in the thread were referencing the PAIR gasket for use with the block-off plates but I'm leaning towards using the O2 sensor gaskets for the new O2 sensor location AND the old O2 sensor location (with block-off plates). I'm just curious what people are using the PAIR gaskets for if that system is being removed?

 

[Irish Reiver]

I just the O2 gasket with OEM block offs. I never moved my O2 sensors so the block off are on the manifold. Has worked well for over a year.

 

[Ppleasants]

I just the O2 gasket with OEM block offs. I never moved my O2 sensors so the block off are on the manifold. Has worked well for over a year.

Perfect; just what I was looking for. Thank you. I ordered them today.

 

[fz1boxer]

I just the O2 gasket with OEM block offs. I never moved my O2 sensors so the block off are on the manifold. Has worked well for over a year.

View attachment 1669778

where did you order those from?when i try to pull up that P/N its shows just gaskets?

 

[Desert Dino]

I never moved my O2 sensors when removed PAIR i used the OEM PAIR gasket and block plate

Keychain- Model 05

 

[Redefined]

I never moved my O2 sensors when removed PAIR i used the OEM PAIR gasket and block plate

Keychain- Model 05

Along with what else? Did you use 2 of those Keychains? I see 2 on my 94 but I'm also being told that I need 3 different Keychains to delete the PAIR. SO I'm kinda confused, it's my DD so I can't just rip it all off and then order parts, hah.